Displaying publications 41 - 60 of 335 in total

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  1. Synergistic effect of optimizing light-emitting diode illumination quality and intensity to manipulate composition of fatty acid methyl esters from Nannochloropsis sp
    Teo CL, Idris A, Zain NAM, Taisir M
    Bioresour Technol, 2014 Dec;173:284-290.
    PMID: 25310864 DOI: 10.1016/j.biortech.2014.09.110
    In the study, the relationship between the quality and intensity of LED illumination with FAMEs produced were investigated. Nannochloropsis sp. was cultivated for 14 days under different intensities of 100, 150 and 200 μmol photons m(-2) s(-1) of red, blue and mixed red blue LED. The findings revealed that suitable combination of LED wavelengths and intensity; (red LED: 150, blue: 100 and mixed red blue: 200 μmol photons m(-2) s(-1)) produced maximum biomass growth and lipid content. It was observed that the quality and intensity of LED significantly influenced the composition of FAMEs. FAMEs produced under blue LED has high degree of unsaturation (DU) and low cetane number while those under red LED has low DU but higher CN. The combination of red blue LED has produced FAMEs with high ignition and lubricating property and also good oxidation stability indicated by the DU and CN values which lies midway between the red and blue.
    Matched MeSH terms: Light*
  2. Estimation of optimum specific light intensity per cell on a high-cell-density continuous culture of Chlorella zofingiensis not limited by nutrients or CO₂
    Imaizumi Y, Nagao N, Yusoff FM, Taguchi S, Toda T
    Bioresour Technol, 2014 Jun;162:53-9.
    PMID: 24747382 DOI: 10.1016/j.biortech.2014.03.123
    To determine the optimum light intensity per cell required for rapid growth regardless of cell density, continuous cultures of the microalga Chlorella zofingiensis were grown with a sufficient supply of nutrients and CO2 and were subjected to different light intensities in the range of 75-1000 μE m(-2) s(-1). The cell density of culture increased over time for all light conditions except for the early stage of the high light condition of 1000 μE m(-2) s(-1). The light intensity per cell required for the high specific growth rate of 0.5 day(-1) was determined to be 28-45 μE g-ds(-1) s(-1). The specific growth rate was significantly correlated to light intensity (y=0.721×x/(66.98+x), r(2)=0.85, p<0.05). A high specific growth rate was maintained over a range of light intensities (250-1000 μE m(-2) s(-1)). This range of light intensities suggested that effective production of C. zofingiensis can be maintained outdoors under strong light by using the optimum specific light intensity.
    Matched MeSH terms: Light*
  3. Enhancing growth and lipid production of marine microalgae for biodiesel production via the use of different LED wavelengths
    Teo CL, Atta M, Bukhari A, Taisir M, Yusuf AM, Idris A
    Bioresour Technol, 2014 Jun;162:38-44.
    PMID: 24736210 DOI: 10.1016/j.biortech.2014.03.113
    Wavelength of light is a crucial factor which renders microalgae as the potential biodiesel. In this study, Tetraselmis sp. and Nannochloropsis sp. as famous targets were selected. The effect of different light wavelengths on growth rate and lipid production was studied. Microalgae were cultivated for 14 days as under blue, red, red-blue LED and white fluorescent light. The growth rate of microalgae was analyzed by spectrophotometer and cell counting while oil production under improved Nile red method. Optical density result showed the microalgae exhibited better growth curve under blue wavelength. Besides, Tetraselmis sp. and Nannochloropsis sp. under blue wavelength showed the higher growth rate (1.47 and 1.64 day(-1)) and oil production (102.954 and 702.366 a.u.). Gas chromatography analysis also showed that palmitic acid and stearic acid which were compulsory components for biodiesel contribute around 49-51% of total FAME from Nannochloropsis sp. and 81-83% of total FAME from Tetraselmis sp.
    Matched MeSH terms: Light*
  4. Intensity of blue LED light: a potential stimulus for biomass and lipid content in fresh water microalgae Chlorella vulgaris
    Atta M, Idris A, Bukhari A, Wahidin S
    Bioresour Technol, 2013 Nov;148:373-8.
    PMID: 24063820 DOI: 10.1016/j.biortech.2013.08.162
    Light quality and the intensity are key factors which render microalgae as a potential source of biodiesel. In this study the effects of various intensities of blue light and its photoperiods on the growth and lipid content of Chlorella vulgaris were investigated by using LED (Light Emitting Diode) in batch culture. C. vulgaris was grown for 13 days at three different light intensities (100, 200 and 300 μmol m(-2)s(-1)). Effect of three different light and dark regimes (12:12, 16:08 and 24:00 h Light:Dark) were investigated for each light intensity at 25°C culture temperature. Maximum lipid content (23.5%) was obtained due to high efficiency and deep penetration of 200 μmol m(-2)s(-1) of blue light (12:12 L:D) with improved specific growth (1.26 d(-1)) within reduced cultivation time of 8 days. White light could produce 20.9% lipid content in 10 days at 16:08 h L:D.
    Matched MeSH terms: Light*
  5. The influence of light intensity and photoperiod on the growth and lipid content of microalgae Nannochloropsis sp
    Wahidin S, Idris A, Shaleh SR
    Bioresour Technol, 2013 Feb;129:7-11.
    PMID: 23232218 DOI: 10.1016/j.biortech.2012.11.032
    Illumination factors such as length of photoperiod and intensity can affect growth of microalgae and lipid content. In order to optimize microalgal growth in mass culture system and lipid content, the effects of light intensity and photoperiod cycle on the growth of the marine microalgae, Nannochloropsis sp. were studied in batch culture. Nannochloropsis sp. was grown aseptically for 9 days at three different light intensities (50, 100 and 200 μmol m(-2) s(-1)) and three different photoperiod cycles (24:0, 18:06 and 12:12 h light:dark) at 23 °C cultivation temperature. Under the light intensity of 100 μmol m(-2) s(-1) and photoperiod of 18 h light: 6 h dark cycle, Nannochloropsis sp. was found to grow favorably with a maximum cell concentration of 6.5×10(7) cells mL(-1), which corresponds to the growth rate of 0.339 d(-1) after 8 day cultivation and the lipid content was found to be 31.3%.
    Matched MeSH terms: Light
  6. Effects of different light source and media on growth and production of phycobiliprotein from freshwater cyanobacteria
    Khatoon H, Kok Leong L, Abdu Rahman N, Mian S, Begum H, Banerjee S, et al.
    Bioresour Technol, 2018 Feb;249:652-658.
    PMID: 29091850 DOI: 10.1016/j.biortech.2017.10.052
    The aim of this study was to determine the effect of different light sources and media (wastewater and BBM) on the growth of Pseudanabaena mucicola and its phycobiliprotein production. Results showed that P. mucicola grown in white light using wastewater as medium attributed higher biomass (0.55 g L-1) and when extracted with water, also showed significantly higher (P 
    Matched MeSH terms: Light
  7. Impact of light spectra on photo-fermentative biohydrogen production by Rhodobacter sphaeroides KKU-PS1
    Tiang MF, Hanipa MAF, Mahmod SS, Zainuddin MT, Lutfi AAI, Jahim JM, et al.
    Bioresour Technol, 2024 Feb;394:130222.
    PMID: 38109981 DOI: 10.1016/j.biortech.2023.130222
    Purple non-sulphur bacteria can only capture up to 10 % light spectra and only 1-5 % of light is converted efficiently for biohydrogen production. To enhance light capture and conversion efficiencies, it is necessary to understand the impact of various light spectra on light harvesting pigments. During photo-fermentation, Rhodobacter sphaeroides KKU-PS1 cultivated at 30 °C and 150 rpm under different light spectra has been investigated. Results revealed that red light is more beneficial for biomass accumulation, whereas green light showed the greatest impact on photo-fermentative biohydrogen production. Light conversion efficiency by green light is 2-folds of that under control white light, hence photo-hydrogen productivity is ranked as green > red > orange > violet > blue > yellow. These experimental data demonstrated that green and red lights are essential for photo-hydrogen and biomass productions of R. sphaeroides and a clearer understanding that possibly pave the way for further photosynthetic enhancement research.
    Matched MeSH terms: Light
  8. Nutritional optimization of Arthrospira platensis for starch and Total carbohydrates production
    Lai YH, Puspanadan S, Lee CK
    Biotechnol Prog, 2019 05;35(3):e2798.
    PMID: 30828976 DOI: 10.1002/btpr.2798
    Present study aims to optimize the production of starch and total carbohydrates from Arthrospira platensis. Growing concerns toward unprecedented environmental issues associated with plastic pollution has created a tremendous impetus to develop new biomaterials for the production of bioplastic. Starch-based biopolymers from algae serve as sustainable feedstock for thermoplastic starch production due to their abundant availability and low cost. A. platensis was cultivated in Zarrouk's medium at 32 ± 1°C and exposed to red light with a photoperiod of 12:12 hr light/dark. Growth kinetics studies showed that the maximum specific growth rate (μmax ) obtained was 0.059 day-1 with the doubling time (td ) of 11.748 days. Subsequently, Zarrouk's medium with different concentrations of sulfur, phosphorus and nitrogen was prepared to establish the nutrient-limiting conditions to enhance the accumulation of starch and total carbohydrates. In this study, the highest starch accumulated was 6.406 ± 0.622 mg L-1 under optimized phosphorus limitation (0.025 g L-1 ) conditions. Nitrogen limitation (0.250 g L-1 ) results demonstrated significant influenced (p 
    Matched MeSH terms: Light
  9. Fulltext Effect of temperature on population growth of copepod, Euterpina acutifrons
    Sitti Raehanah Muhamad Shaleh, Marlena Amatus, Najamuddin Abdul Basri, Rossita Shapawi
    Borneo Journal of Marine Science and Aquaculture, 2020;4(1):57-61.
    MyJurnal
    This study was aimed at determining the optimum temperature for culturing the copepod, Euterpina acutifrons. The trial was conducted for 10 days in chambers at temperatures of 25⁰C, 27⁰C, 29⁰C and 31⁰C. Ten adult individuals of the copepod were randomly collected and placed into three replicate experimental flasks for each treatment. Throughout the trial, the salinity, light intensity, and photoperiod were maintained at 30 ±2psu, 100molm-2s-1 and 12:12 light-dark cycle, respectively. The copepods were fed with 80,000cell/ml Isochrysis sp. daily. At the end of the trial, the total numbers of E. acutifrons nauplii, copepodites and adults were determined and counted using Sedgwick-Rafter. The highest population was found at 27⁰C with mean total population of 800±100 individuals from an initial of 10 individuals. This was followed by those reared at 25⁰C and 29⁰C where the population counts were 700±100 individuals and 367±115 individuals, respectively. At the 31⁰C, all the copepod specimens were found dead on day 5th. Statistical analysis showed that the temperature had a significant effect (P
    Matched MeSH terms: Light
  10. Melatonin, environmental light, and breast cancer
    Srinivasan V, Spence DW, Pandi-Perumal SR, Trakht I, Esquifino AI, Cardinali DP, et al.
    Breast Cancer Res Treat, 2008 Apr;108(3):339-50.
    PMID: 17541739
    Although many factors have been suggested as causes for breast cancer, the increased incidence of the disease seen in women working in night shifts led to the hypothesis that the suppression of melatonin by light or melatonin deficiency plays a major role in cancer development. Studies on the 7,12-dimethylbenz[a]anthracene and N-methyl-N-nitrosourea experimental models of human breast cancer indicate that melatonin is effective in reducing cancer development. In vitro studies in MCF-7 human breast cancer cell line have shown that melatonin exerts its anticarcinogenic actions through a variety of mechanisms, and that it is most effective in estrogen receptor (ER) alpha-positive breast cancer cells. Melatonin suppresses ER gene, modulates several estrogen dependent regulatory proteins and pro-oncogenes, inhibits cell proliferation, and impairs the metastatic capacity of MCF-7 human breast cancer cells. The anticarcinogenic action on MCF-7 cells has been demonstrated at the physiological concentrations of melatonin attained at night, suggesting thereby that melatonin acts like an endogenous antiestrogen. Melatonin also decreases the formation of estrogens from androgens via aromatase inhibition. Circulating melatonin levels are abnormally low in ER-positive breast cancer patients thereby supporting the melatonin hypothesis for breast cancer in shift working women. It has been postulated that enhanced endogenous melatonin secretion is responsible for the beneficial effects of meditation as a form of psychosocial intervention that helps breast cancer patients.
    Matched MeSH terms: Light; Lighting/adverse effects*
  11. Fulltext Genes and genealogy of the guppy fish, Poecilia reticulata
    Khoo, Gideon, Lim, Tit Meng, Phang, Violet Pan Eng
    Buletin Persatuan Genetik Malaysia, 2006;12(1):5-7.
    MyJurnal
    Since the early 1950’s, Singapore is internationally known as the guppy-breeding centre. At least 40 different colour varieties of guppies are cultured in Singapore, with each farm specialising in 10 to 15 varieties. These fancy varieties have been developed by skilful farmers through intensive and continual selective breeding. Genes controlling background body pigmentation such as albino (a), blond (b), gold (g) and blue (r) are autosomally inherited and recessive to their wild-type alleles which produce drab olive-brown background coloration. Colour patterns which are superimposed onto wild-type background coloration are due to genes located on the sex chromosomes. These
    sex-linked colour genes are dominant and sex-limited to males as their expression requires male hormones. Y-linked colour pattern genes carried by males are inherited only along the paternal line while X-linked genes are present in both sexes. Among the guppy varieties produced locally, only two Y-linked genes, Ssb and Sst, that control snakeskin tail and body patterns, respectively, have been found in varieties with snakeskin-like reticulations. Single colour genes that are both X- and Y-linked produce red (Rdt), blue (Blt), green (Grt), black (Bt) and variegated (Var) patterns
    on the caudal fin. The black caudal-peduncle of the Tuxedo variety is the result of Bcp, a gene that is both X- and Ylinked. Different combinations of colour pattern genes and background pigmentation genes as well as interactions among them give rise to various colour phenotypes. For
    instance, the inclusion of Bcp in Snakeskin varieties causes black reticulations on the tail fin to be replaced by large, coarse black spots. Neon coloration is produced by interactions between the Ln (light turquoise) gene with Blt, Rdt and Bcp.
    Matched MeSH terms: Light
  12. Fulltext Animal leptospirosis in Malaya: 3. Incidence in rats by sex, weight and age
    Gordon Smith CE, Turner LH, Harrison JL, Broom JC
    Bull World Health Organ, 1961;24(6):807-16.
    PMID: 20604093
    In previous papers it has been demonstrated that ground-dwelling rats are the principal reservoir of leptospirosis in Malaya. The present paper considers the distribution of infection by sex and weight in the ten principal rat species. There appears to be a general tendency for females to be infected more frequently than males, but significant differences were demonstrated only in R. sabanus (more than three times as many females as males infected) and R. whiteheadi. In Malaya, where seasonal changes are minimal, weights can be used as a good index of age in rats. In rat species with a low incidence of infection the incidence appeared to rise steadily with age. In species with a medium incidence the infection rate rose at first with age, fell in the 6-8-month age-group, and then rose again. In high-incidence species the rate rose rapidly from the second month.There appear to be three types of enzootic infection; (1) intensive transmission of a single serogroup in a crowded population of rats of a single species (transmission probably being through urinary contamination of damp soil); (2) low-intensity transmission of several serogroups among ground-rats frequenting wet places (probably with urinary transmission); and (3) low-intensity transmission of several serogroups among ground-rats in dry places (the transmission may be venereal).
    Matched MeSH terms: Light
  13. Regenerated cellulose membrane as bio-template for in-situ growth of visible-light driven C-modified mesoporous titania
    Mohamed MA, W Salleh WN, Jaafar J, Mohd Hir ZA, Rosmi MS, Abd Mutalib M, et al.
    Carbohydr Polym, 2016 08 01;146:166-73.
    PMID: 27112862 DOI: 10.1016/j.carbpol.2016.03.050
    Visible light driven C-doped mesoporous TiO2 (C-MTiO2) nanorods have been successfully synthesized through green, low cost, and facile approach by sol-gel bio-templating method using regenerated cellulose membrane (RCM) as nanoreactor. In this study, RCM was also responsible to provide in-situ carbon sources for resultant C-MTiO2 nanorods in acidified sol at low temperatures. The composition, crystallinity, surface area, morphological structure, and optical properties of C-MTiO2 nanorods, respectively, had been characterized using FTIR, XRD, N2 adsorption/desorption, TEM, UV-vis-NIR, and XPS spectroscopy. The results suggested that the growth of C-MTiO2 nanorods was promoted by the strong interaction between the hydroxyl groups of RCMs and titanium ion. Optical and XPS analysis confirmed that carbon presence in TiO2 nanorods were responsible for band-gap narrowing, which improved the visible light absorption capability. Photocatalytic activity measurements exhibited the capability of C-MTiO2 nanorods in degradation of methyl orange in aqueous solution, with 96.6% degradation percentage under visible light irradiation.
    Matched MeSH terms: Light*
  14. Novel Ag/cellulose-doped CeO2 quantum dots for efficient dye degradation and bactericidal activity with molecular docking study
    Ikram M, Hayat S, Imran M, Haider A, Naz S, Ul-Hamid A, et al.
    Carbohydr Polym, 2021 Oct 01;269:118346.
    PMID: 34294353 DOI: 10.1016/j.carbpol.2021.118346
    In the present study, the novel Ag/cellulose nanocrystal (CNC)-doped CeO2 quantum dots (QDs) with highly efficient catalytic performance were synthesized using one pot co-precipitation technique, which were then applied in the degradation of methylene blue and ciprofloxacin (MBCF) in wastewater. Catalytic activity against MBCF dye was significantly reduced (99.3%) for (4%) Ag dopant concentration in acidic medium. For Ag/CNC-doped CeO2 vast inhibition domain of G-ve was significantly confirmed as (5.25-11.70 mm) and (7.15-13.60 mm), while medium- to high-concentration of CNC levels were calculated for G + ve (0.95 nm, 1.65 mm), respectively. Overall, (4%) Ag/CNC-doped CeO2 revealed significant antimicrobial activity against G-ve relative to G + ve at both concentrations, respectively. Furthermore, in silico molecular docking studies were performed against selected enzyme targets dihydrofolate reductase (DHFR), dihydropteroate synthase (DHPS), and DNA gyrase belonging to folate and nucleic acid biosynthetic pathway, respectively to rationalize possible mechanism behind bactericidal potential of CNC-CeO2 and Ag/CNC-CeO2.
    Matched MeSH terms: Light
  15. Measuring initial enamel erosion with quantitative light-induced fluorescence and optical coherence tomography: an in vitro validation study
    Chew HP, Zakian CM, Pretty IA, Ellwood RP
    Caries Res, 2014;48(3):254-62.
    PMID: 24481141 DOI: 10.1159/000354411
    BACKGROUND: Measurement of initial enamel erosion is currently limited to in vitro methods. Optical coherence tomography (OCT) and quantitative light-induced fluorescence (QLF) have been used clinically to study advanced erosion. Little is known about their potential on initial enamel erosion.

    OBJECTIVES: To evaluate the sensitivity of QLF and OCT in detecting initial dental erosion in vitro.

    METHODS: 12 human incisors were embedded in resin except for a window on the buccal surface. Bonding agent was applied to half of the window, creating an exposed and non-exposed area. Baseline measurements were taken with QLF, OCT and surface microhardness. Samples were immersed in orange juice for 60 min and measurements taken stepwise every 10 min. QLF was used to compare the loss of fluorescence between the two areas. The OCT system, OCS1300SS (Thorlabs Ltd.), was used to record the intensity of backscattered light of both areas. Multiple linear regression and paired t test were used to compare the change of the outcome measures.

    RESULTS: All 3 instruments demonstrated significant dose responses with the erosive challenge interval (p < 0.05) and a detection threshold of 10 min from baseline. Thereafter, surface microhardness demonstrated significant changes after every 10 min of erosion, QLF at 4 erosive intervals (20, 40, 50 and 60 min) while OCT at only 2 (50 and 60 min).

    CONCLUSION: It can be concluded that OCT and QLF were able to detect demineralization after 10 min of erosive challenge and could be used to monitor the progression of demineralization of initial enamel erosion in vitro.

    Matched MeSH terms: Light
  16. Graphene oxide as a structure-directing agent for the two-dimensional interface engineering of sandwich-like graphene-g-C3N4 hybrid nanostructures with enhanced visible-light photoreduction of CO2 to methane
    Ong WJ, Tan LL, Chai SP, Yong ST
    Chem Commun (Camb), 2015 Jan 18;51(5):858-61.
    PMID: 25429376 DOI: 10.1039/c4cc08996k
    A facile one-pot impregnation-thermal reduction strategy was employed to fabricate sandwich-like graphene-g-C3N4 (GCN) nanocomposites using urea and graphene oxide as precursors. The GCN sample exhibited a slight red shift of the absorption band edge attributed to the formation of a C-O-C bond as a covalent cross linker between graphene and g-C3N4. The GCN sample demonstrated high visible-light photoactivity towards CO2 reduction under ambient conditions, exhibiting a 2.3-fold enhancement over pure g-C3N4. This was ascribed to the inhibition of electron-hole pair recombination by graphene, which increased the charge transfer.
    Matched MeSH terms: Light
  17. Band gap engineered, oxygen-rich TiO2 for visible light induced photocatalytic reduction of CO2
    Tan LL, Ong WJ, Chai SP, Mohamed AR
    Chem Commun (Camb), 2014 Jul 4;50(52):6923-6.
    PMID: 24841282 DOI: 10.1039/c4cc01304b
    A facile and dopant-free strategy was employed to fabricate oxygen-rich TiO2 (O2-TiO2) with enhanced visible light photoactivity. Such properties were achieved by the in situ generation of oxygen through the thermal decomposition of the peroxo-titania complex. The O2-TiO2 photocatalyst exhibited high photoactivity towards CO2 reduction under visible light.
    Matched MeSH terms: Light
  18. A highly emissive and stable zinc(ii) metal-organic framework as a host-guest chemopalette for approaching white-light-emission
    Cai H, Xu LL, Lai HY, Liu JY, Ng SW, Li D
    Chem Commun (Camb), 2017 Jun 27.
    PMID: 28654101 DOI: 10.1039/c7cc03350h
    A new adenine-containing metal-organic framework (MOF), [Zn4O(adenine)4(benzene-1,3-dicarboxylate)4Zn2] (named as ZnBDCA), was synthesized solvothermally. ZnBDCA possesses high quantum yield (>50%) and nano-channels that can encapsulate acriflavine molecules to build a host-guest chemopalette for approaching white-light emission.
    Matched MeSH terms: Light
  19. Oxygen vacancy induced Bi2WO6 for the realization of photocatalytic CO2 reduction over the full solar spectrum: from the UV to the NIR region
    Kong XY, Choo YY, Chai SP, Soh AK, Mohamed AR
    Chem Commun (Camb), 2016 Dec 06;52(99):14242-14245.
    PMID: 27872917
    Photocatalytic CO2 reduction over the UV-Vis-NIR broad spectrum was realized for the first time. The presence of surface oxygen vacancy defects on Bi2WO6 resulted in significant photocatalytic enhancement over the pristine counterpart under UV and visible light irradiation. Meanwhile, the photocatalytic responsiveness of Bi2WO6-OV was successfully extended to the NIR region.
    Matched MeSH terms: Light
  20. Photodynamic activity of plant extracts from Sarawak, Borneo
    Jong WW, Tan PJ, Kamarulzaman FA, Mejin M, Lim D, Ang I, et al.
    Chem Biodivers, 2013 Aug;10(8):1475-86.
    PMID: 23939795 DOI: 10.1002/cbdv.201200303
    Photodynamic therapy (PDT) is a medical treatment that involves the irradiation of an administered photosensitizing drug with light of a particular wavelength to activate the photosensitizer to kill abnormal cells. To date, only a small number of photosensitizers have been clinically approved for PDT, and researchers continue to look for new molecules that have more desirable properties for clinical applications. Natural products have long been important sources of pharmaceuticals, and there is a great potential for discovery of novel chemotypes from under-explored biodiversities in the world. The objective of this study is to mine the terrestrial plants in Sarawak, Borneo Island, for new photosensitizers for PDT. In a screening program from 2004 to 2008, we prepared and studied 2,400 extracts from 888 plants for their photosensitizing activities. This report details the bioprospecting process, preparation and testing of extracts, analysis of the active samples, fractionation of four samples, and isolation and characterization of photosensitizers.
    Matched MeSH terms: Light*
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